Locks are provided on doors to restrict entry through an opening controlled by the door and also to prevent unauthorized persons from gaining entry. One problem with most vehicle door locks is that without some sort of retention device, the lock cylinder may be quickly and easily “punched out” or otherwise detached from the door. What is needed is a retainer assembly which will prevent an unauthorized person from removing the lock cylinder, or at least make it difficult and time-consuming for this to be done.